1. Field of the Invention
This invention relates to liquid propellant guns utilizing differential area pistons to provide continued or regenerative injection of a liquid propellant into the combustion chamber and, particularly, to such guns in which there are a plurality of coaxial pistons arranged so as to provide for relative piston action as a means for controlling propellant injection and, particularly, in configurations permitting the insertion of a projectile through the breech structure of the gun.
2. Description of the Prior Art
An extensive summary of the prior art appears in the patent application of R. E. Mayer, Ser. No. 840,104 filed Oct. 6, 1977, and companion applications Bulman Ser. No. 840,074 and Algera Ser. No. 840,075 also filed Oct. 6, 1977. The patents to R. A. Jukes et al, U.S. Pat. No. 3,138,990, June 30, 1964; D. P. Tassie, U.S. Pat. No. 4,023,463, May 17, 1977; and A. R. Graham, U.S. Pat. No. 4,050,349, Sept. 27, 1977; cited in the applications noted above, are exemplary of that prior art. In general, the references cited show differential pressure piston devices for forcing liquid propellant from a reservoir chamber into a combustion chamber to constitute a regenerative system.
Two specific items of prior art not previously referred to deserve particular mention. U.S. Pat. No. 4,033,224 to J. W. Holtrop, July 5, 1977 (assigned to the U.S. Government), discloses a receiver for a rapid fire bolt action bulk or batch-loaded liquid propellant gun in which the structure constituting the load injection pump and the propellant control valve physically resemble the coaxial pistons according to one or more of the implementations of the invention disclosed and claimed in this specification. Similarity, however, is limited to physical resemblances of those parts as Holtrop's gun is a batch-loaded rather than a regenerative liquid propellant gun and does not address the question of pressure control during firing. The Patent of V. W. Jaqua, U.S. Pat. No. 4,281,582 issued Aug. 4, 1981, discloses a regenerative hypergolic, i.e., a two component liquid propellant having a fuel and an oxidizer, using a differential area injection piston to inject the hypergolic propellant into a combustion chamber. Jacqua also biases the injection piston hydraulically by means of a circumferential raised portion on the piston rod of the injection piston which acts as a second differential area piston. Therefore, to the extent that the Jacqua Application constitutes a complete disclosure, it teaches the use of hydraulic pressure to provide a "snubbing" (sic) effect to assist in control of movement of the injection piston in a regenerative liquid propellant gun.